Math Problem Statement

write x as a linear combination of a and b, round answer to nearest tenth if applicable

Write vector x as a linear combination of vectors a and b, rounding the answer to the nearest tenth if applicable.

Solution

To express vector x as a linear combination of vectors a and b, we want to find scalars α\alpha and β\beta such that:

x=αa+βbx = \alpha a + \beta b

From the image:

  • The vector a points from the origin to approximately (2, -1).
  • The vector b points from the origin to approximately (2, 2).
  • The vector x points from the origin to approximately (-7, -5).

Now we need to solve the equation:

(75)=α(21)+β(22)\begin{pmatrix} -7 \\ -5 \end{pmatrix} = \alpha \begin{pmatrix} 2 \\ -1 \end{pmatrix} + \beta \begin{pmatrix} 2 \\ 2 \end{pmatrix}

This leads to the system of linear equations:

7=2α+2β-7 = 2\alpha + 2\beta 5=α+2β-5 = -\alpha + 2\beta

Let's solve this system to find α\alpha and β\beta.The solution to the system of equations is:

α=23andβ=176\alpha = -\frac{2}{3} \quad \text{and} \quad \beta = -\frac{17}{6}

Rounding these to the nearest tenth, we get:

α0.7andβ2.8\alpha \approx -0.7 \quad \text{and} \quad \beta \approx -2.8

Thus, the vector x can be written as:

x0.7a2.8bx \approx -0.7a - 2.8b

Would you like more details or have any questions?

Here are some related questions you could explore:

  1. What is the geometric meaning of expressing one vector as a linear combination of others?
  2. How do we know if vectors a and b are linearly independent?
  3. What happens if a and b were parallel vectors?
  4. How would this method apply in three dimensions?
  5. Can we express x as a linear combination if a and b were in different quadrants?

Tip: Always check if vectors are linearly independent before expressing one as a combination of others, as this ensures a unique solution.

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Math Problem Analysis

Mathematical Concepts

Vector algebra
Linear combination
Systems of linear equations

Formulas

x = αa + βb
System of equations: -7 = 2α + 2β, -5 = -α + 2β
Solution for α and β

Theorems

Linear independence and dependence of vectors

Suitable Grade Level

College level / Advanced high school